JP3325628B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a copper film for filling a contact hole having a surface step in an integrated circuit.

[0002]

2. Description of the Related Art As the degree of integration of integrated circuits increases, the current density in wiring on a chip tends to increase. For example, in the scaling rule of a MOS transistor,
The channel length was reduced from 1.5 μm to 0.75 μm (dimension scaling factor: λ = 2.00), and the drain voltage V _D
Is changed from 5 V to 3 V (voltage scaling coefficient: K
= 1.67), the scaling factor of the current density I _D / S is 2.88 (λ ³ / K ² ), and the current density is 2.88
It is known to double.

As the degree of integration of an integrated circuit increases, the current density of wiring on a chip increases. For this reason, in the conventional aluminum wiring, since aluminum has a high diffusion rate even at a relatively low temperature, there is a problem that use in a region where the current density is high leads to disconnection,
Attempts have been made to use heat-resistant metals such as copper for wiring instead of aluminum.

As a conventional method for forming a copper film, there is a method as shown in FIG. 2, for example. According to this method, an interlayer insulating film 102 is deposited on a semiconductor substrate 101 on which a desired element is formed (FIG. 2A), and an upper portion of regions 150 and 151 of the semiconductor substrate 101 where electrical connection is required. Is etched to form a contact hole 204 (FIG. 2B). Next, a copper film 203 is formed from above by a sputtering method (FIG. 2C). Further, in order to prevent diffusion of copper atoms into the interlayer insulating film 102, a copper film having a laminated structure in which a film such as titanium nitride (TiN) is applied to the upper or lower layer of the copper film 203 may be used.

[0005]

However, in a high-density integrated circuit, the wiring density is high and the diameter of the contact hole is required to be smaller. In addition, the step coverage of the copper film at the contact hole was not sufficient. Therefore, when the diameter of the contact hole is reduced, an increase in resistance in the contact hole portion, a disconnection due to a current accompanying the operation of the element, and a disconnection due to a temperature change when an insulating protective film is formed on the wiring occur. There was a problem.

[0006]

According to the present invention, in a method of manufacturing a semiconductor device, a step of depositing an insulating film on a surface of a semiconductor substrate, a step of forming a contact hole in the insulating film, Depositing an aluminum film on the semiconductor substrate surface including the bottom and side surfaces of
A copper film by the high temperature sputtering saw including a step of depositing on the aluminum film, prior by the high temperature sputtering
The semiconductor substrate temperature is between the aluminum film and the copper film.
Forming an aluminum-copper alloy layer between the films of
The object is solved by the temperature at which the luminium-copper alloy layer has fluidity .

According to the present invention, in a method of manufacturing a semiconductor device, a step of forming a first wiring layer on a surface of a semiconductor substrate, and forming an interlayer insulating film on a surface of the semiconductor substrate including the first wiring layer. The step of depositing, the step of forming a contact hole in the interlayer insulating film, the step of depositing an aluminum film on the surface of the semiconductor substrate including the bottom and side surfaces of the contact hole, and forming the copper film by a high-temperature sputtering method. Covering the aluminum film, filling the contact hole with copper, and forming a second wiring layer.
The semiconductor substrate temperature by the high-temperature sputtering method.
Is a gap between the aluminum film and the copper film.
Forming a aluminum-copper alloy layer and forming the aluminum-copper alloy
This problem is solved by the temperature at which the gold layer has fluidity .

[0008]

According to the method of manufacturing a semiconductor device of the present invention, an aluminum film is first deposited to fill a contact hole provided in an insulating film deposited on a surface of a semiconductor substrate, and then a copper film is formed by high-temperature sputtering. Formed. This allows
An alloy layer of aluminum and copper is formed, the fluidity of the copper on the surface of the semiconductor substrate is increased, and the contact holes are filled with copper.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1A to 1D are cross-sectional views in the order of steps of a method for manufacturing a semiconductor device according to one embodiment of the present invention. First of all,
An interlayer insulating film 102 having a thickness of about 1.0 μm is formed on a semiconductor substrate 101 on which required elements are formed. When silicon (Si) is used as a main material of a semiconductor substrate, silicon dioxide (SiO ₂ ) is most often used for an interlayer insulating film. If the step of forming an element on the semiconductor substrate is a planar method, since the other surface of the semiconductor substrate is already covered with the insulating film, the interlayer insulating film 102 is formed on the diffusion window used last for diffusion. Just do it. Next, as shown in FIG. 3B, the interlayer insulating film 102 above the regions 150 and 151 of the semiconductor substrate where a predetermined electrical connection is required is dry-etched to have a predetermined shape with a diameter of about 0.4 μm. Is formed. Next, as shown in FIG. 3C, an aluminum film 103 having a thickness of about 0.05 to 0.2 μm is formed by DC magnetron sputtering.

Finally, as shown in FIG. 1D, a copper film 104 having a thickness of about 0.2 to 0.5 μm is formed on the aluminum film 103 at a substrate temperature of 500 ° C. by DC magnetron sputtering. At this time, the aluminum and copper of the previously formed aluminum film 103 mix with each other to form an aluminum-copper alloy layer 105. At a substrate temperature of 500 ° C., the aluminum-copper alloy layer 105 is closer to a liquid phase and has higher fluidity than the individual elements of aluminum and copper. Thereby, the contact hole 106 is filled with copper with good step coverage,
An electrical connection with low resistance and high reliability is performed.

While the preferred embodiment has been described, it is not intended to limit the invention. It is obvious to those skilled in the art that the method of manufacturing a semiconductor device according to the present invention can be applied to fill contact holes for connection between wiring layers in a multilayer wiring as well as contact holes for connecting elements and wirings of a semiconductor substrate as in the embodiment. Will.

[0012]

As described above, according to the present invention, after an aluminum film is formed on the surface of a semiconductor substrate including the bottom and side surfaces of a contact hole, a copper film is formed by a high-temperature sputtering method, and the contact hole is buried at the same time. . As a result, even when the contact hole is reduced, the step coverage of the copper film is sufficiently ensured, the contact hole can be filled without gaps, and a copper wiring having low resistance and high reliability can be formed.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views in the order of steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIGS. 2A to 2C are cross-sectional views in the order of steps in a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Semiconductor substrate 102 Interlayer insulating film 103 Aluminum film 104 Copper film 105 Aluminum-copper alloy film 106 Contact hole 150, 151 A region of the semiconductor substrate where electrical connection is required

Claims (2)

(57) [Claims] 1. A method of manufacturing a semiconductor device, comprising: a step of applying an interlayer insulating film on a surface of a semiconductor substrate; a step of forming a contact hole in the interlayer insulating film; and a semiconductor including a bottom surface and side surfaces of the contact hole. a step of depositing an aluminum film on the substrate surface, viewed including the step of depositing a copper film by a high-temperature sputtering method on the aluminum film, the semiconductor substrate temperature by the high temperature sputtering method, before
Aluminum film is formed between the aluminum film and the copper film.
Forming an aluminum-copper alloy layer and forming the aluminum-copper alloy layer
A method for manufacturing a semiconductor device, characterized in that the temperature is fluid . 2. A method for manufacturing a semiconductor device , comprising: forming a first wiring layer on a surface of a semiconductor substrate; and depositing an interlayer insulating film on a surface of the semiconductor substrate including the first wiring layer. Forming a contact hole in the interlayer insulating film, forming an aluminum film on the surface of the semiconductor substrate including the bottom and side surfaces of the contact hole, and forming a copper film on the aluminum film by a high-temperature sputtering method. and wearing copper by viewing including the step of forming a second wiring layer together to fill the contact holes, the semiconductor substrate temperature by the high temperature sputtering method, before
Aluminum film is formed between the aluminum film and the copper film.
Forming an aluminum-copper alloy layer and forming the aluminum-copper alloy layer
A method for manufacturing a semiconductor device, characterized in that the temperature is fluid .